1. Field of the Invention
This invention relates to an organic electroluminescent element having improved durability and especially to materials for an organic luminous layer and an organic electron transport layer, which are components of the organic EL element.
2. Related Arts
Recently, in accordance with diversification of information apparatuses, the demand has been growing for flat-type display elements which can manage with less electric power and smaller space than cathode-ray tubes (CRT). Included in such flat-type display elements are crystalline liquid display elements and plasma display elements, and drawing special attention among them is an electroluminescent (hereinafter referred to as EL) element, which is a self-luminescent type and can provide clear display.
Among such EL elements, an organic EL element has an advantage of capable of being driven with low voltage because it is a charge injected from an electrode and recombined in an organic luminous material, thereby exhibiting luminescence. It has another advantage of capable of obtaining theoretically any desired luminous colors by modifying molecular structure of the organic luminous material for an organic luminous layer.
Meanwhile, selection of organic materials for the organic EL element greatly affects its characteristics, and especially its durability, whose improvement is a crucial subject at present. Unfortunately, most of the organic materials which are being used for an organic luminous layer and an organic electron transport layer are insufficient in their film-forming properties, thereby deteriorating the durability of the EL element. Thus, organic materials having satisfactory film-forming properties not to damage the durability of the EL element are very limited.
The present application is an improvement of Japanese Patent Application NO. 3-222793, which proposes luminous layer materials and electron transport layer materials capable of improving the durability of EL elements by solving the above-mentioned problems.